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Napa, CA

[Line Problem] DSL light keeps turning/flashing red; losing DSL

All of a sudden, only for the past... oh... say, maybe three days, my DSL connection is dropping... after pretty much flawless service for years.

Sometimes it happens while I'm using it, right in the middle of an email download, or surfing, etc.; but mostly it happens if the machine just sits there, on and connected, but me not sitting at the keyboard doing anything. In other words, I'll sit down at the computer (which is already on and logged-in to), and I'll try to hit a web page, or download email, and it just stalls out... can't seem to connect to the web site or mail servers.

Then I look down at the lights on the DSL modem, and the activity light's not doing anything, and the Internet light is dark, and the DSL light may be green, or it may be red... just depends. Most of the time, the DSL light ultimately starts flashing red, even if it was solid green when I first looked down at it.

So then I reach around behind and unplug power, wait 10 or so seconds, and reconnect. The DSL modem goes through all the normal training and the DSL light flashes red, then green, then stays green; then the Internet light comes on; and then if I try again to hit a web site the activity light starts flashing and the site appears (though sometimes after failing such that I have to close the browser, relaunch it, and try again... which, at that point, always seems to succeed).

So then it runs for a while... sometimes an hour or two, sometimes the rest of the day and/or evening (there seems no pattern to it)...

...and then even the next morning (if I leave the machine on all night), it's still fine when I try to hit something in the browser, and it lets me download email okay; and it may even run most of the day like that, just fine, before it finally fails again... and then it's a repeat of the above.

Today (Sat 29 Jan 2011) has been particularly bad, for some reason. The machine was on and Internet-connected all night, as usual. I sat down at the machine and tried to hit a site and it just wouldn't go. The activity light was dark, the Internet light was dark, but the DSL light was solid green...

...though, about a half minute later, before my eyes, it started flashing red. And, again, I unplugged DSL modem power, waited 10 seconds, reconnected, watched it try to train...

...only this time, it failed. The DSL light stayed flashing red.

So I unplugged again; waited 10 seconds; reconnected and watched it try to train-up... and this time it succeeded.

But it has inexplicably failed again two or three more times since then today...

...hence the reason I'm finally here, seeking some help.

It's a regular AT&T DSL line (not U-verse); at 1.5Mbps-down/384Kbps-up.

I've checked speed today -- twice -- using two or three different speed test tools, and connecting with New Jersey, Chicago and San Francisco...

...and all of my speeds are pretty much what they have always been, which is around 1.2Mbps to 1.3Mbps down, and 280Kbps to 320Kbps up... which is pretty much all that this location has ever been able to achieve on this account.

My CO is NAPACA01 located at 1300 Clay St, Napa, CA, 94559. As the crow flies, I'm maybe 2.5 to perhaps 3 miles from the CO. Who knows how many actual cable feet that is.

The connection is good analog copper from the CO to me, with no digital duplexing devices anywhere in the circuit. In fact, when I first ordered the service back in... I think it was 2003... I asked for more than a mere turn-on at the CO, and I insisted that a tech come out to the premises and we stood there and tested pairs until we found the quietest and best. So it's been a fairly decent connection from the beginning... and always reliable, in any case.

I've also walked the property and physically inspected the lines to make sure that nothing physical has happened. Phone service is good, with no strange sounds in the white noise when I clear dialtone. Everything seems fine on that score.

It's also not the router (though I checked all its settings, and rebooted it a time or two, just for grins). The Ethernet light on the DSL modem never goes dark during any of this. There's always a good connection between the DSL modem and the router.

And the DSL modem seems fine (though it is the second one, the first one having gone bad for some reason in 2008).

I also, just to be thorough, swapped-out the DSL filter with a brand new one that I happened to have in a box, still sealed in its blister packaging. The problem persists.

Heck, I even repaired/rebuilt TCP/IP in Windows, just for grins (even though I knew that that had nothing whatsoever to do with whatever is the problem).

I also use OpenDNS instead of AT&T's DNS, but that's not configured in the DSL modem. That's happening in the router; and this problem has nothing to do with that, in any case. The DNS that I use wouldn't have anything to do with the DSL modem's DSL light starting to flash red and completely losing the connection. But I thought I'd mention it, just to be thorough.

Though I concede that maybe it could be the DSL modem going bad again (though I doubt it), my gut from 33 years in IT and telecom suggests to me that this is a line/carrier issue of some kind...

...though, obviously, that's what I'm here to have someone help me investigate/confirm/deny, etc.

Allowing myself to be guided by this...

»AT&T West FAQ » What information do you need in order to help me with my DSL problem? are my answers to those questions:

DSL TYPE: Express 1.5Mbps/384Kbps

DSL MODEM TYPE: Motorola 2210-02

ROUTER: D-Link EBR 2310 (wired, with four-port switch) (believe me, the router's not the problem)

DSL MODEM LOGIN INFO: In the DSL modem (and it's correct)

DSL MODEM LIGHTS: Details are above, but basically the activity light goes stops flickering and goes dark; then the Internet light goes from solid green to dark; and then, finally, the DSL light goes from solid green to flashing red. The Ethernet light always stays solid green, as does the Power light.

PHYSICAL CONNECTIONS and FILTER: All fine... as indicated above, I not only checked them, but I swapped-out the filter with a new one; and I even physically walked the property to make sure that nothing has obviously happened to the wires running from the house out to the telephone pole.

POWERED OFF/ON THE DSL MODEM: Yes, as explained above, every time it has happened, I power off, wait 10 (or more) seconds, then power back on... and every time but one it trained-up normally and resumed just fine. Only once did it not so do, and I simply powered-off/on again, and it finally trained-up okay and resumed normally. And speeds, after each time, are fine.

PHONE LINE NOISE: None. Sounds like it always has both with dialtone, and if I clear it and just listen to the white noise by pressing a DTMF key. I also called a friend who knows telephony and asked him if he could hear anything, and he said the line sounded fine. And the DSL filter's obviously working, because I can't hear the DSL noise on the regular analog phone line with the telephone handset.

STATISTICS FROM THE DSL MODEM (all of the tables):

ADSL Information
Line State Up
Modulation DMT
Data Path Fast

To Modem To Internet
Max Allowed Speed (kbps) 1536 384
SN Margin (dB) 16.0 21.0
Line Attenuation (dB) 9.0 4.0
Loss of Signal 0 0
Loss of Frame 0 0
CRC Errors 0 1

ATM Information
VPI / VCI 0/35
Protocol PPPoE

In Octets 14987525
In Errors 0
In Unicast Packets 15001
In Non Unicast Packets 0
In Discard Packets 0

Out Octets 2562268
Out Errors 0
Out Unicast Packets 12860
Out Non Unicast Packets 0
Out Discard Packets 0

PPPoE Information
Session Status: Up
Server MAC Address: 00:02:3b:02:a7:30
Session ID: 49380

IP Information
Internet Address
Internet Gateway
DNS Servers

IP interfaces
Address Netmask Name Ethernet 100BT

Routing Table
Destination Netmask Gateway Interface
- - WAN vcc1 Ethernet 100BT

LAN Information
Modem IP Address
Modem Netmask
DHCP Address

Devices on LAN
IP Address MAC Address Name Status 00:1c:f0:c3:34:c3 Active

Ethernet Information
MAC Address 00:1d:6b:88:17:28

In Octets 15115686
In Errors 0
In Unicast Packets 14992
In Non Unicast Packets 3369
In Discard Packets 0

Out Octets 2406216
Out Errors 0
Out Unicast Packets 12825
Out Non Unicast Packets 68
Out Discard Packets 0

...and I can provide the technicial readout, or the log, or the configuration page, or whatever.

SPEED TEST RESULTS: For some reason the AT&T speed test site says it's "In Maintenance" at the moment; but I've tested using several sites today, and they all show about the same thing, as explained earlier, herein, and that's just under 1.3Mbps down, and just under 300Kbps up, which is pretty much what it has always been. I just did it again at SPEEDTEST.NET and here are the links...

Napa, CA to San Francisco
» ··· 9413.png

Napa, CA to Los Angeles
» ··· 2155.png

Napa, CA to Chicago
» ··· 3110.png

PINGTEST.NET - Napa, CA to Los Angeles
» ··· 9723.png

PINGTEST.NET - Napa, CA to Chicago
» ··· 9774.png

If there's anyone here who works for AT&T who'd like to actually test the line with me, just email me and we can set it up...

gregg at greggdeselms dot com

Thoughts? Suggestions? Anyone?

San Jose, CA

Re: [Line Problem] DSL light keeps turning/flashing red; losing

Thanks for the very thorough write-up! One simple question....what's the serial number on the Motorola modem?

While you doubt that you've gotten two bad modems, you're thinking too logically. The 2210 is the biggest POS PacBell/SBC/AT&T has ever distributed and they tend to fail far too often, many with the exact symptoms you describe. Nothing else in the info you've provided makes me suspect a line problem, but of course anything's possible.


Napa, CA
Modem Name Motorola
Model 2210-02
Serial Number 42473256
Software Version 7.7.3r5

I have to admit that I've always thought that the 2210 seemed kinda' cheap looking and feeling. Plus, I hate silver-colored stuff (not that that matters to this thread... but I'm just sayin').

And I'm trying to remember, now, exactly how it happened, but as I recall, back when AT&T replaced the 2210 in 2008, I had made an argument about its poor quality; and how irritated I was that since it was out of warranty I had to purchase a new one, and how all these people I knew who had Siemens Speedstream 4100b's never had any troubles with them for years and years; and how it's not right to deprive me of DSL service while I wait for a new one so I should have a back-up, blah, blah, blah.

And since I was making this argument to a supervisor (whom I always ask for, right out of the gate, whenever I call), and since I'm pretty good at making such arguments, she put me on hold and checked with someone about whether she could do it, and then came back on the line and told me she was having a 4100b sent to me, too... for free. In other words, I purchased a new 2210, but got it AND a 4100b for the cost of the 2210 alone. She suggested that I use the 4100b, but keep the 2210 as the backup that I was suggesting/complaining that I should have.

However, I fired-up the new 2210 and just started using it; and I have the brand spankin' new 4100b sitting on the shelf not ten feet away from me where I'm sitting as I type this.

Do you believe/agree that the 4100b's a far superior device?

And it sounds like you believe, in any case, that if I swap the 2210 for the 4100b, all symptoms will cease. No?

Interestingly, the symptom returned in a slightly different form about three hours after I started this thread. The failure, then, was that the activity light went dark, but the Internet light stayed solid green, as did the DSL light, but I couldn't connect to anything to save my life. Perhaps if I had waited long enough, the DSL light would have gone to flashing red again, but I didn't. I got frustrated that it was seemingly happening again and reset the modem again... and things started working again.

But not a single problem since.

Of course, that might not mean anything. Who knows.

Anyway... thoughts?

San Jose, CA
That serial number is certainly in the range of ones where I've experienced failures of one sort or another. As bad as I think the 2210 is, the 4100b is at the extreme opposite end of the spectrum. I think most of the regulars in here will agree that it's the best modem ever provided by AT&T. It was so solid that when they discontinued them I drove to many of the BestBuy's in the Bay Area and bought up their remaining stock! Alas, I've used all of those up replacing failed modems for my clients but my own personal 4100b is still going strong.

So I wouldn't even wait for the 2210 to start giving you problems again. I'd slam the 4100b in place and move on down the road.


Napa, CA

1 edit
Thank you, so much, for that input.

Turns out the 2210 made the decision for me this very morning.

I was using the Internet just fine, and then all of a sudden when I tried to view a tutorial video on a web site, everything stalled.

I looked down at the 2210 and the activity light was dark, and I looked down at in just in time to see the Internet light go out, then about 8 seconds later the DSL light went from solid green to flashing red...

...and it never came back. Even after I reset the 2210, and the DSL light initially came on okay for maybe two seconds, it went back to flashing red, and just stayed that way, no matter how many times I power reset/rebooted the 2210. I just let it sit there for a while and it eventually even stopped retrying and just settled-in with nothing but the power light, and the Ethernet light on.

Before swapping it out for the 4100b, and also mistakenly thinking that ATT needed the serial number of the 4100b in its database (as it had tol me that needed the serial number of the 2210, before), I called AT&T tier 2 tech support (which I always ask for since the front line tech support people usually can't punch their way out of a technolgical paper sack)...

...and he said that until I had a modem logged-in, he couldn't do much more than see that DSL was on on the line, and that the CO could detect no anomalies; but he needed that 4100b working in order to properly test. Plus he said that he was virtually certain that it was the modem, and not the line, in any case.

So, I swapped them out...

...and right out of the gate there was a problem because the 4100b wants the same IP address as my router, so I couldn't, initially, get into the modem to enter the login and password...

...and I had all my cables so zip tied and pretty that it was a temporary nightmare taking the EBR-2310 temporarily out of the circuit (which I did because there was no way I was going to make the tech guy sit there and wait for me while I tried to remember where in the router I could change its IP address)...

...but once that was done, I got into the modem, entered the login/password, and it trained-up real pretty; then he tested the line and said it looked about as good as a DSL circuit can get.

So that was that. It was the 2210 after all, just like you suspected. So I thanked him and we ended the call.

Turns out he didn't need the serial number of the 4100b; that that was something that AT&T only needed for 2210 devices. Apparently, any 4100b from anywhere -- including, like you said, a Best Buy or wherever -- would have worked.

It was funny, though: I asked the AT&T tech if the 4100b was really good and he said that it was discontinued, but that from hs experience, it was one of the best that AT&T ever sold. He called it one of the "more simple," devices AT&T has ever used; but he said that when it comes to something like a basic DSL modem, "sometimes simpler is better." I asked if I could get another one and it took him a few seconds to stop laughing.

Anyway, after we hung-up, I removed the 4100b from the circuit and put the router back in, logged-in, and then tried to figure out how to change its IP (which I finally did), and then I put it all back together with the modem and router in the circuit, rebooted everything, and everything was good to go.

SEE: » ··· 7466.png
SEE: » ··· 3589.png

I assume that both of those tests will be a little better after the 4100b's been on for a week straight... or at least that's been my experience with these things.

So... anyway, live and learn, I guess. I just didn't want to believe it was the 2210. I guess I just couldn't believe that I had burned through a second one in what seemed like so short a time.

Speaking of burned: After I got everything working again, I don't know what made me do it but before I tossed the 2210 into the electronics recyling bin, I picked it up (now cooled all the way down) and took a good strong sniff through the vent louvers...

...and if you've been doing this for a while, then you know what I mean when I say that I got the strong "burnt circuit board" smell from the 2210. It was really strong.

So, obviously, the 2210 fried. What a crappy device, eh?

I've mounted the 4100b differently... in a place with better ventilation. Since its lights are on top (versus the 2210's on the front... er... well... kind of front/top), I can more easily mount the 4100b on the wall and still easily see its lights when I need to; and there was an excellent spot right next to where I have a little cooling fan just kind of gently circulating air around the back side of my notebook's docking station. So it'll be better, all 'round, ongoing, I think.

Anyway... thanks, so much for your help! Sure wish you still had some 4100b's... I'd buy one from 'ya. [grin]


San Jose, CA
I don't know anything about the serial number "requirement" -- I've never had to contact AT&T when replacing a 2210 with another (something I only did before it became apparent that most all of the ones being shipped were junk).

You will get max performance right out of the gate, there's nothing magical that happens after a week. You may be remembering the thing about leaving a modem on for 10 days when you first get DSL. That's because some circuits start out at a slower speed and they gradually bump up the limits if everything remains stable. But that's only for new installs, and then only on certain types of connections and speed profiles.

Your download speed is right where an Express profile should be, although the upload is a bit low. I see that you were connecting to servers in IL, somehow. When you go to, hover your mouse pointer over the rotating gold star and pick San Francisco. You should see something around 1.3 down and around .32 up.

Yeah, the smell is typical because all of the failures I've seen are from overheating. The 2210 was just poorly designed from the start.

Glad your back up and working properly, may your 4100b live long and prosper.